9/22 Preclass Copy this chart & info onto a new piece of paper:

Transcription

1 9/22 Preclass Copy this chart & info onto a new piece of paper: Kilo (K) Hecto (H) Deka (Da) meters (m) liters (L) grams (g) deci (d) centi (c) milli (m) Km = 0.01 Hm= 0.1 Dam = 1 m= 10 dm = 100cm = 1000mm For units of LITERSor GRAMS, it works the same way: KL = 0.01 HL= 0.1 DaL= 1 m= 10 dl= 100cL= 1000ml Kg= 0.01 Hg= 0.1 Dag= 1 m= 10 dg= 100cg= 1000mg

2 International System of Units SI Units, or the Metric System AP EnviSci September 22, 2010 Ms. Johnson

3 What do I write down?? The text in GREEN. Example: 9/22/10: Metric System & Conversions Review

4 Who uses the metric system? Scientists ALL over the world Officially, 99% of ALL countries in the world use the metric system. Who s not (officially) using the International System? The USA Burma Liberia

5 What is the metric system? Because it s awesome! And rational! The metric system is an international system of measurement. The SI system uses decimals, or powers of 10: 10 millimeters = 1 centimeter 1000 grams = 1 kilogram In contrast, the English system uses unusual increments: 16 oz. = 1 pound 12 inches = 1 foot 4 quarts = 1 gallon

6 When was the metric system started? First proposed in 1670 in France Adopted by almost the whole world during the last century The USA agreed to convert in the 1970 s, but We didn t completely follow-through Change is hard

7 Examples: meter

8 Example: Gram

9 Example: Liter

10 Examples: degrees Celsius

11 Example: Kilometer 10 Km = 6 miles

12 Examples: kilogram

13 Example: milliliter

14 Example: centimeter

15 How does the metric system work? Metric Prefixes tell it all This metric scale helps us convert units in the metric system: Kilo (K) Hecto (H) Deka (Da) meters (m) liters (L) grams (g) deci (d) centi (c) milli (m) As you convert from one unit to another, the value does not change. Only how we describe the UNITS changes. For example: Do you have the same value if you hold $1, 10 dimes, or 100 pennies.? Yes! The only difference is the monetary UNIT that you hold.

16 How it works, continued Metric Prefixes tell it all This metric scale helps us convert units in the metric system: Kilo (K) Hecto (H) Deka (Da) Meters (m) Liters (L) Grams (g) deci (d) centi (c) milli (m) To convert from one unit to the other, simply move the decimal point! This multiplies by 10 each time you move the decimal to the right. The # gets BIGGER This divides by 10 each time you move the decimal to the left. Then # gets SMALLER

17 Units of Measure: Meter (m): the unitsof length the straight-line distance between two points Liter (L): the unitsof volume the size of an object in 3-dimensional space Grams (g): the unitsof mass the measure of the amount of matter in an object Seconds (s), the units of time

18 Prefixes Definition: Prefix = to place in front Prefixes go in front of units of measure: K H Da -- d c m But Ms. Johnson, how can I remember this?!? King Henry Died --- drinking chocolate milk

19 Practice! Directions: Write the word, underline the prefix, and list the type of measurement. Example: cm = centimeter, length Kg = Hg = L = Dag = mm = dg = cl= mg

20 Practice! Directions: Write the word, underline the prefix, and list the type of measurement. Example: cm = centimeter, length 1. m = 2. dm = 3. g = 4. Km = 5. mg = 6. dl= 7. DaL= 8. cm

21 So. Which would you rather have: 1 H$ or 1 c$??

22 Practice! Convert the following: 1) 1 m = cm 2) 1 m = Km 3) 1 Km = cm 4) 5 Kg = g 5) 5 Dag = cg 6) 25 ml= L 7) 75 dl= L 8) 9.8 L = HL

23 Convertingto change units Conversion factor:a # that expresses two different units that have the same value Ex: 100 pennies = $1 Using this as a fraction, we create the # 1 Ex: 100 pennies = 1 $1 Multiplying any number by 1 does NOT changing it s value

24 Create your bag of conversion factors: 1 m = inches 2.2 lbs = 1 Kg 1 kg = 1000 g 100 cm = 1 m Practice these problems

25 Practice! Convert the following: 155 Hm= m 155 m = Dam 155 Kg = cg 2 Kg = Dag 2 Dag = cg 6.1 ml= L 3.14 dl= L 0.6 L = HL

26 Where can we use the metric system? Everywhere! Beginning January 1, 2010, the European Union Council Directive 80/181/EEC (Metric Directive) will allow the use of only metric units, and prohibit the use of any other measurements for most products sold in the European Union (EU). Going well beyond labeling, the Metric Directive will make the sole use of metric units obligatory in all aspects of life in the European Union, extending to areas such as product literature and advertising. From: t_2010.pdf, Accessed 9/22/09